Bokeh - From Horizontal to Vertical
You can simulate the ellipsoidal bokeh created by anamporphic lenses by changing the ratio on the depth of field settings.

The defalut value for ratio of 1:1 will give you a circular shape, while a larger or smaller number will make the defocused elements deform in an ellipsoidal shape. 

A value higher than 1 will deform the defocused areas on vertical ellipsoids (the most common anamorphic lenses will compress the image on a 2:1 aspect)

Conversely to deform horizontally use numbers smaller than 1 





To create custom shapes for the bokeh (As described in this link: http://www.diyphotography.net/can-you-make-computerized-shaped-bokeh/):

Create a plane with a hole that has the shape of the bokeh you want.

Place the plane really close in front of the camera (adjust the clipping distance if necessary, so that the camera can see the object)..

Set the depth of field on the camera, and render.



Click on the image to enlarge



Click on the image to enlarge